Pawlowski, others support federal bill that would require review of all gun purchases.

Every time a gun is legally sold in Pennsylvania, a background check is run on the potential buyer — except if the transaction is a private sale of a rifle or shotgun.

In other states, criminal background checks are required — with exceptions for guns purchased at gun shows.

A number of Pennsylvania mayors, including Allentown's, want to get rid of the exceptions.

Allentown Mayor Ed Pawlowski, Whitehall Township Mayor Ed Hozza, Northampton Mayor Thomas Reenock and state Rep. Mike Schlossberg, all Democrats, joined representatives of CeaseFirePa, a coalition of gun violence prevention organizations, at Allentown City Hall on Wednesday to support a federal bill calling for background checks for all gun purchases.

"What we're talking about today is really the most common-sense, simple solution," said Shira Goodman, executive director of CeaseFirePA, a partner of Mayors Against Illegal Guns, which has the support of 200 mayors in Pennsylvania.

Under pressure to revisit gun laws after the massacre of schoolchildren in Newtown, Conn., in December, the House of Representatives is considering the Fix Gun Checks Act , sponsored by Congresswoman Carolyn McCarthy, a New York Democrat whose husband was killed and son wounded in a 1993 mass shooting on a Long Island Rail Road train.

Pawlowski said an estimated 6.6 million guns transfer hands each year without a background check, an obvious route for people with potentially criminal intentions. Pawlowski likened the gap in coverage to an airport with two passenger check-in lines — one with security checks, and one without them.

"Which one do you think criminals will choose?" he said. The background check system, which Pawlowski called "highly effective," already is in place in Pennsylvania, so adding private sales of long guns such as rifles and shotguns wouldn't overburden the system, he said. "We don't think this is a big 'ask'," he added.

The Pennsylvania Instant Check System is a database and communications network system designed to handle 1.2 million calls a year, according to the State Police 2011 Annual Firearms Report. It searches state records covering criminal history, juvenile justice, involuntary commitments to mental health institutions, protection from abuse claims and others. It intersects with the national system, which checks public records from the federal government and other states.

FBI statistics show 78,211 gun sales were denied nationwide in 2011. According to the state police report, background checks stopped 9,600 sales statewide that year.

Because background checks only identify if a person is legally able to own a gun, expanding them would not violate the Second Amendment to the U.S. Constitution, Pawlowski said.

"Political leaders in D.C. should not be able to duck on this issue," he said.

Hozza also called on Washington to ensure that the looming sequester, the broad spending cut that is scheduled to begin Friday, not hamper the federal government's ability to carry out checks expeditiously.

Schlossberg, of Allentown, derided the National Rifle Association's opposition to universal background checks, saying more arms will not make society safer.

"The solution to gun violence in America is not more guns," he said, "any more than the solution to alcoholism in America is more alcohol or the solution to drug addiction in America is more drugs."

In public statements and advertising campaigns, NRA officials have said universal checks would lead to registration of owners, and that would lay the groundwork for government seizure of weapons.

That stance, however, puts the gun rights organization at odds with a vast majority of the American public. Goodman noted. She cited a January poll by Quinnipiac University in Connecticut, which showed that 92 percent of respondents supported universal background checks. Among gun owners, the poll shows, 91 percent supported the check.

Because only private long gun sales are not subject to background checks in Pennsylvania, supporters of the tighter law acknowledge that it would have relatively little impact locally on crime.